Wireless UV-A LEDs-driven AOP in the treatment of agro-industrial wastewaters.

A wireless UV-A LEDs lab-scale reactor powered by a resonant inductive coupling (RLC) system was built to maximize the UV photon absorption of agro-industrial wastewaters. The UV-A LEDs (λ = 365 nm) energy was supplied through a magnetic field generated inside of the photoreactor by induction coils placed on the external wall made of polyvinyl chloride. Immersing the light sources in the wastewater increases the photon transfer efficiency and the reaction rate. Maximum magnetic field and optical irradiance were obtained at 26.8 and 27.0 kHz, respectively. As proof-of-concept, elderberry wastewater (EW), olive washing wastewater (OWW) and white and red winery wastewaters (WWW and RWW) were treated combining the wireless UV-A LEDs with the Advanced Oxidation Process (AOP) - Fenton reagent. Fenton experiments were performed using [Fe2+] = 10 mg L-1, [H2O2] = 500 mg L-1, pH = 3 and a reaction time of 4 h. With EW a DOC removal of 35% (k = 0.0696 h-1) was achieved, whereas adding the wireless UV-A LEDs (f = 26.8 kHz) 53% was attained (k = 0.1722 h-1). The Electric Energy per Order (EEO) for the wireless UV-A LEDs consumption was calculated (EEO LEDs = 48.7 kWh m-3 order-1) and for all the remain equipment (air pump, RC box and power amplifier), EEO total = 495 kWh m-3 order-1. Experiments with OWW presented a DOC removal of 62% and a EEO LEDs = 40.5 kWh m-3 order-1; RWW shown 40% of DOC removal and a EEO LEDs = 68.4 kWh m-3 order-1, while with WWW 35% of DOC removal and a EEO LEDs = 79.8 kWh m-3 order-1 were obtained. This work shows that wireless UV-A LEDs can be a promising alternative to conventional UV lamps and wired LEDs in the treatment of real wastewaters. However, optimization of the induction system is still needed, as well as the number and wavelength of the LEDs (e.g. UV-C LEDs) to reduce the overall treatment costs.

Photocatalytic degradation of an agro-industrial wastewater model compound using a UV LEDs system: kinetic study.

An ultraviolet light emitting diode (UV-A LED) system was built to test the capability of performing heterogeneous photocatalysis using TiO2 P25. The LEDs maximum wavelength is 365 nm with an irradiance power of 85 W m-2. The device was tested in batch and continuous (CSTR) mode in a laboratorial scale reactor. The degradation of an agro-industrial wastewater model compound (p-hydroxybenzoic acid, pHBA) was investigated, assessing the effect of different experimental conditions such as pH, pHBA and TiO2 concentration keeping constant the UV-A LEDs power and temperature. The photodegradation of different concentrations of pHBA with [TiO2] = 500 mg L-1, IUV = 85 W m-2 and a T = 21 °C were analysed by pseudo-first order kinetics. The results were applied to the Langmuir-Hinshelwood model yielding kc = 0.885 mg L-1 min-1 and kLH = 0.217 L mg-1. In a comparative experiment the UV-A LEDs system showed faster kinetics (k = 0.0134 min-1) than solar radiation (IUV = 23 W m-2; k = 0.0077 min-1), with [pHBA] = 75 mg L-1 and [TiO2] = 500 mg L-1. The values of the Electric Energy per Order (EEO) = 115 kWh m-3 order-1 and the Specific Applied Energy (ESAE) = 318 kWh mol-1 order-1 were obtained with [TiO2] = 1000 mg L-1 and [pHBA] = 50 mg L-1. Analogous results were obtained ([TiO2] = 500 mg L-1) in a CSTR with a slight decrease in the first order kinetic constant due to the "non-ideal" reactor: from 0.0284 to 0.0158 min-1 and from 0.0143 to 0.00825 min-1 with [pHBA] = 50 mg L-1 and 75 mg L-1, respectively. This work shows that photocatalytic reactors with UV-A LEDs can advantageously replace conventional UV mercury lamps based reactors in the photodegradation of phenolic compounds.

A simple dispersive solid phase extraction clean-up/concentration method for selective and sensitive quantification of biogenic amines in wines using benzoyl chloride derivatisation.

A simple, quick, cheap and green dispersive solid phase extraction (dSPE) method followed by benzoyl chloride pre-column derivatisation for HPLC-UV determination of twelve biogenic amines (BAs) in wines is proposed for the first time. The dSPE using a strong cation exchange resin increased the selectivity and sensitivity of the analysis by elimination of interfering compounds and a five-fold enrichment of BAs. The method presented an adequate precision and linearity with detection limits ranging from 0.133 to 0.509 mg/L. Recoveries ranging from 72 to 99% prove the accuracy of the method for determining BAs in red, white and Tawny Port wine samples yielding chromatograms clean from interferents. The method was applied successfully to the analysis of 31 young red wines from different Portuguese wine regions. The dSPE method although has a potential of broader application to other food matrixes, other derivatisation procedures than benzoyl chloride and other detectors.

Integrated aerobic biological-chemical treatment of winery wastewater diluted with urban wastewater. LED-based photocatalysis in the presence of monoperoxysulfate.

The oxidation of Winery Wastewater (WW) by conventional aerobic biological treatment usually leads to inefficient results due to the presence of organic substances, which are recalcitrant or toxic in conventional procedures. This study explores the combination of biological and chemical processes in order to complete the oxidation of biodegradable and non-biodegradable compounds in two sequential steps. Thus, a biological oxidation of a diluted WW is carried out by using the activated sludge process. Activated sludge was gradually acclimated to the Diluted Winery Wastewater (DWW). Some aspects concerning the biological process were evaluated (kinetics of the oxidation and sedimentation of the sludge produced). The biological treatment of the DWW led to a 40-50% of Chemical Oxygen Demand (COD) removal in 8 h, being necessary the application of an additional process. Different chemical processes combining UVA-LEDs radiation, monoperoxysulfate (MPS) and photocatalysts were applied in order to complete the COD depletion and efficient removal of polyphenols content, poorly oxidized in the previous biological step. From the options tested, the combination of UVA, MPS and a novel LaCoO3-TiO2 composite, with double route of MPS decomposition through heterogeneous catalysis and photocatalysis, led to the best results (95% of polyphenol degradation, and additional 60% of COD removal). Initial MPS concentration and pH effect in this process were assessed.

Macroscopic structure of the fin-rays and their annuli in pectoral and pelvic fins of Chinook Salmon, Oncorhynchus tshawytscha.

Light microscopy, enzyme clearing, and staining techniques were used to describe the structure of fin-rays in pectoral and dorsal fins of adult and juvenile chinook salmon,Oncorhynchus tshawytscha. In addition, several decalcification agents, fixatives, and staining methods were employed to demonstrate and determine the nature of the fin-ray annulus (yearly growth ring). Etched, transverse sections of fin-rays were examined by scanning electron microscopy (SEM). A description is provided of specific morphological regions along the length of fin-rays in both fins. Each ray consists of parallel halves, medial and lateral hemisegments, which diverge proximally and embrace underlying radial cartilages and are segmented distally. Fibrocartilage masses are associated with bone and hyaline cartilage in the proximal regions. There is evidence of periosteal, and perhaps endochondral, osteogenesis in the fin-rays. A novel fixation-staining method is described to depict the fin ray annulus in adult chinook salmon. Transverse sections of rays of adults, but not juveniles, demonstrate alternating narrow-dark and wide-light purple bands following prolonged decalcification/fixation in Bouin's fluid only with subsequent hematoxylin-eosin staining. The dark and light bands correspond to translucent (annuli) and opaque zones, respectively, in dried, unstained sections in transmitted light and in backscatter SEM. In conjunction with different light microscopic staining procedures, etched, transverse sections of fin-ray bone in SEM suggest that annuli are a manifestation of an ordered regionalization of the extracellular matrix of the bone in the fin-rays. J. Morphol. 239:297-320, 1999. © 1999 Wiley-Liss, Inc.